It is known from EP 1 435 758 A2 to incorporate input elements such as switches into the lid of a hearing instrument, e.g. the lid of its battery compartment. When the lid is moved into a closed position, two contact elements of the lid get into electrical contact with corresponding contact elements of the hearing instrument's body. The number of different functions, e.g. switches or potentiometers, that can be incorporated in the lid is limited by the number of contact elements. It is desirable to have a variety of different input elements on the lid while keeping the number of contact elements as low as possible.
In many hearing instruments the integrated circuits (ICs) and the passive components like surface mounted device (SMD) resistors and capacitors are combined in a subassembly or electronic circuit assembly, also called a hybrid circuit. Such a hybrid circuit is combined with electromechanical components such as manual switches, and electro-acoustic components such as microphones and loudspeakers to constitute a hearing instrument.
It is desirable to minimise the number of input/output (IO) contacts that are needed to interface the hybrid circuit with the other components. Each such contact requires a bonding pad for contacting a conductor such as a wire to the hybrid circuit. This takes up space on the circuit and necessitates a bonding operation, increasing cost and reducing reliability.
Typical input devices for a hearing instrument are analog and digital wheels, various types of switches, including e.g. push buttons, seesaw switches, locking (engaging) and non-locking switches. Each switch requires one associated IO contact. The switch, when closed, connects the IO contact to a reference voltage such as ground.
The term “hearing instrument” or “hearing device”, as understood here, denotes on the one hand hearing aid devices that are medical devices improving the hearing ability of individuals, primarily according to diagnostic results. Such hearing aid devices may be outside-the-ear hearing aid devices or in-the-ear hearing aid devices. On the other hand, the term stands for devices which may improve the hearing of individuals with normal hearing e.g. in specific acoustical situations such as in a very noisy environment or in concert halls, or which may even be used in context with remote communication or with audio listening, for instance as provided by headphones.
The hearing devices as addressed by the present invention are so-called active hearing devices which comprise at the input side at least one acoustical to electrical converter, such as a microphone, at the output side at least one electrical to mechanical converter, such as a loudspeaker, and which further comprise a signal processing unit for processing signals according to the output signals of the acoustical to electrical converter and for generating output signals to the electrical input of the electrical to mechanical output converter. In general, the signal processing circuit may be an analog, digital or hybrid analog-digital circuit, and may be implemented with discrete electronic components, integrated circuits, or a combination of both.